Effects of phosphoinositide 3-kinase on protease-induced acute and chronic lung inflammation, remodeling, and emphysema in rats

PI3K signalling in chronic obstructive pulmonary disease and opportunities for therapy

Chronic obstructive pulmonary disease (COPD) is a chronic lung disease characterised by airway inflammation and progressive obstruction of the lung airflow. Current pharmacological treatments include bronchodilators, alone or in combination with steroids, or other anti-inflammatory agents, which have only partially contributed to the inhibition of disease progression and mortality. Therefore, further research unravelling the underlying mechanisms is necessary to develop new anti-COPD drugs with both lower toxicity and higher efficacy. Extrinsic signalling pathways play crucial roles in COPD development and exacerbations. In particular, phosphoinositide 3-kinase (PI3K) signalling has recently been shown to be a major driver of the COPD phenotype. Therefore, several small-molecule inhibitors have been identified to block the hyperactivation of this signalling pathway in COPD patients, many of them showing promising outcomes in both preclinical animal models of COPD and human clinical trials. In this review, we discuss the critically important roles played by hyperactivated PI3K signalling in the pathogenesis of COPD. We also critically review current therapeutics based on PI3K inhibition, and provide suggestions focusing on PI3K signalling for the further improvement of the COPD phenotype. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Interferon gamma induces inflammatory responses through the interaction of CEACAM1 and PI3K in airway epithelial cells

BACKGROUND

Interferon gamma (IFNγ) plays an important role in the development of chronic lung diseases via the production of inflammatory mediators, although the exact mechanism remains unclear. The present study aimed at investigating the potential mechanisms by which IFNγ induced over-production of interleukins through the interaction between carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) and phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) pathway.

METHODS

IFN-γ induced over-production of interleukin (IL) 6 and IL8, and RNA expression of CEACAM1 and its subtypes or PI3K and its subtypes in human bronchial epithelial cells (HBE). The production of IL6 and IL8 or cell proliferation and movement were also evaluated in cell^CEACAM1- or cell^CEACAM1+ after the induction of IFN-γ. Roles of PI3K subtype proteins, e.g. PI3Kp110α/δ, Akt, p110α/γ/δ/β/mTOR, PI3Kp110α/δ/β, PI3Kp110δ, or pan-PI3K in IFN-γ-induced CEACAM1 subtype alterations were furthermore validated using those proteins of PI3K subtypes.

RESULTS

CEACAM1, especially CEACAM1-S isoforms, was significantly up-regulated in HBE cells after treatment with IFN-γ. CEACAM1 played roles in expression of IL-6 and IL-8, and facilitated cellular proliferation and migration. IFN-γ up-regulated the expression of CEACAM1 in airway epithelial cells, especially CEACAM1-S isoforms, promoting cellular proliferation, migration, and the production of inflammatory factors. PI3K (p110δ)/Akt/mTOR pathway was involved in the process of IFN-γ-upregulated CEACAM1, especially CEACAM1-S. On the other hand, CEACAM1 could promote the activation of PI3K/Akt/mTOR pathway.

CONCLUSION

IFN-γ could induce inflammatory responses, cellular growth and proliferation through the interaction of CEACAM1 (especially CEACAM1-S isoforms) and PI3K(p110δ)/Akt/mTOR in airway epithelial cells, which might be new alternative of future therapies against epithelial transition from inflammation to cancer.

Activation of p70S6 Kinase-1 in Mesenchymal Stem Cells Is Essential to Lung Tissue Repair

All‐trans retinoic acid (ATRA) or mesenchymal stem cells (MSCs) have been shown to promote lung tissue regeneration in animal models of emphysema. However, the reparative effects of the combination of the two and the role of p70S6 kinase‐1 (p70S6k1) activation in the repair process have not been defined. Twenty‐one days after intratracheal instillation of porcine pancreatic elastase (PPE), MSC and/or 10 days of ATRA treatment was initiated. Thirty‐two days later, static lung compliance (Cst), mean linear intercepts (MLIs), and alveolar surface area (S) were measured. After PPE, mice demonstrated increased values of Cst and MLI, and decreased S values. Both ATRA and MSC transfer were individually effective in improving these outcomes while the combination of ATRA and MSCs was even more effective. The combination of p70S6k1^−/− MSCs transfer followed by ATRA demonstrated only modest effects, and rapamycin treatment of recipients with wild‐type (WT) MSCs and ATRA failed to show any effect. However, transfer of p70S6k1 over‐expressing‐MSCs together with ATRA resulted in further improvements over those seen following WT MSCs together with ATRA. ATRA activated p70S6k1 in MSCs in vitro, which was completely inhibited by rapamycin. Tracking of transferred MSCs following ATRA revealed enhanced accumulation and extended survival of MSCs in recipient lungs following PPE but not vehicle instillation. These data suggest that in MSCs, p70S6k1 activation plays a critical role in ATRA‐enhanced lung tissue repair, mediated in part by prolonged survival of transferred MSCs. p70S6k1‐activated MSCs may represent a novel therapeutic approach to reverse the lung damage seen in emphysema. stemcellstranslationalmedicine2018;7:551–558

Actinidia chinensis Planch root extract inhibits cholesterol metabolism in hepatocellular carcinoma through upregulation of PCSK9

Actinidia chinensis Planch root extract (acRoots) is a traditional Chinese medicine with anti-tumor efficacy. To investigate the mechanisms responsible for this activity, we examined the effects of acRoots on cholesterol metabolism in hepatocellular carcinoma (HCC). mRNA chip analysis was used to identify the metabolic genes regulated by acRoots. The effects of acRoots on cholesterol synthesis and uptake were evaluated by measuring intracellular cholesterol levels and 3,3′-dioctadecylindocarbocyanine-labeled low-density lipoprotein (Dil-LDL) uptake. Expression of metabolic genes was analyzed using quantitative reverse transcription PCR, western blotting, and flow cytometry. acRoots reduced the viability of LM3 and HepG2 cells at 5 mg/mL and HL-7702 cells at 30 mg/mL. Gene expression profiling revealed that treatment with acRoots altered expression of genes involved in immune responses, inflammation, proliferation, cell cycle control, and metabolism. We also confirmed that acRoots enhances expression of PCSK9, which is important for cholesterol metabolism. This resulted in decreased LDL receptor expression, inhibition of LDL uptake by LM3 cells, decreased total intracellular cholesterol, and reduced proliferation. These effects were promoted by PCSK9 overexpression and rescued by PCSK9 knockdown. Our data demonstrate that acRoots is a novel anti-tumor agent that inhibits cholesterol metabolism though a PCSK9-mediated signaling pathway.

Lipopolysaccharide-induced CCN1 production enhances interleukin-6 secretion in bronchial epithelial cells

Acute lung injury/acute respiratory distress syndrome (ALI/ARDS) is a clinical complication caused by primary or secondary lung injury, as well as by systemic inflammation. Researches regarding molecular pathophysiology of ALI/ARDS are immerging with an ultimate aim towards developing prognostic molecular biomarkers and molecule-based therapy. However, the molecular mechanisms concerning ALI/ARDS are still not completely understood. The purpose of the present study was to identify a crucial role of CCN1 in inflammatory microenvironment during ALI/ARDS and focus on a potential communication between CCN1 and interleukin-6 (IL-6) in the airway epithelial cells. Our data illustrated that the expression levels of CCN1 and IL-6 in bronchoalveolar lavage fluid (BALF) in a lipopolysaccharide (LPS)-induced ALI mouse model were significantly elevated and the pulmonary expression of CCN1 was restricted to bronchial epithelial cells. Interestingly, both endogenous and exogenous CCN1 stimulated IL-6 production in vitro. Furthermore, LPS-induced IL-6 production in a bronchial epithelial cell line was blocked by CCN siRNA whereas CCN1 induced by LPS was sensitive to PI3K inhibition. Together, our data indicate a linear signal pathway, LPS-CCN1-IL-6, existing in bronchial epithelial cells after LPS exposure. This finding may represent an additional mechanism and a novel target for development of therapy and biomarker on ALI/ARDS.

Regulatory mechanisms of TGF-β1-induced fibrogenesis of human alveolar epithelial cells

Pulmonary fibrosis is characterized by an extensive activation of fibrogenic cells and deposition of extracellular matrix (ECM). Transforming growth factor (TGF)‐β1 plays a pivotal role in the pathogenesis of pulmonary fibrosis, probably through the epithelial‐ to‐mesenchymal transition (EMT) and ECM production. The present study investigates potential mechanism by which TGF‐β1 induces EMT and ECM production in the fibrogenesis of human lung epithelial cells during pulmonary fibrosis. The expression of EMT phenotype and other proteins relevant to fibrogenesis were measured and the cell bio‐behaviours were assessed using Cell‐IQ Alive Image Monitoring System. We found that TGF‐β1‐induced EMT was accompanied with increased collagen I deposition, which may be involved in the regulation of connective tissue growth factor (CTGF) and phosphoinositide 3‐kinase (PI3K) signalling pathway. Treatment with PI3K inhibitors significantly attenuated the TGF‐β1‐ induced EMT, CTGF expression and collagen I synthesis in lung epithelial cells. The interference of CTGF expression impaired the basal and TGF‐β1‐stimulated collagen I deposition, but did not affect the process of EMT. Our data indicate that the signal pathway of TGF‐β1/PI3K/CTGF plays an important role in the fibrogenesis of human lung epithelial cells, which may be a novel therapeutic approach to prevent and treat pulmonary fibrosis.

A Chronic Obstructive Pulmonary Disease Susceptibility Gene, FAM13A, Regulates Protein Stability of β-Catenin

RATIONALE

A genetic locus within the FAM13A gene has been consistently associated with chronic obstructive pulmonary disease (COPD) in genome-wide association studies. However, the mechanisms by which FAM13A contributes to COPD susceptibility are unknown.

OBJECTIVES

To determine the biologic function of FAM13A in human COPD and murine COPD models and discover the molecular mechanism by which FAM13A influences COPD susceptibility.

METHODS

Fam13a null mice (Fam13a(-/-)) were generated and exposed to cigarette smoke. The lung inflammatory response and airspace size were assessed in Fam13a(-/-) and Fam13a(+/+) littermate control mice. Cellular localization of FAM13A protein and mRNA levels of FAM13A in COPD lungs were assessed using immunofluorescence, Western blotting, and reverse transcriptase-polymerase chain reaction, respectively. Immunoprecipitation followed by mass spectrometry identified cellular proteins that interact with FAM13A to reveal insights on FAM13A's function.

MEASUREMENTS AND MAIN RESULTS

In murine and human lungs, FAM13A is expressed in airway and alveolar type II epithelial cells and macrophages. Fam13a null mice (Fam13a(-/-)) were resistant to chronic cigarette smoke-induced emphysema compared with Fam13a(+/+) mice. In vitro, FAM13A interacts with protein phosphatase 2A and recruits protein phosphatase 2A with glycogen synthase kinase 3β and β-catenin, inducing β-catenin degradation. Fam13a(-/-) mice were also resistant to elastase-induced emphysema, and this resistance was reversed by coadministration of a β-catenin inhibitor, suggesting that FAM13A could increase the susceptibility of mice to emphysema development by inhibiting β-catenin signaling. Moreover, human COPD lungs had decreased protein levels of β-catenin and increased protein levels of FAM13A.

CONCLUSIONS

We show that FAM13A may influence COPD susceptibility by promoting β-catenin degradation.

A Genome-Wide Association Study of Emphysema and Airway Quantitative Imaging Phenotypes

RATIONALE

Chronic obstructive pulmonary disease (COPD) is defined by the presence of airflow limitation on spirometry, yet subjects with COPD can have marked differences in computed tomography imaging. These differences may be driven by genetic factors. We hypothesized that a genome-wide association study (GWAS) of quantitative imaging would identify loci not previously identified in analyses of COPD or spirometry. In addition, we sought to determine whether previously described genome-wide significant COPD and spirometric loci were associated with emphysema or airway phenotypes.

OBJECTIVES

To identify genetic determinants of quantitative imaging phenotypes.

METHODS

We performed a GWAS on two quantitative emphysema and two quantitative airway imaging phenotypes in the COPDGene (non-Hispanic white and African American), ECLIPSE (Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints), NETT (National Emphysema Treatment Trial), and GenKOLS (Genetics of COPD, Norway) studies and on percentage gas trapping in COPDGene. We also examined specific loci reported as genome-wide significant for spirometric phenotypes related to airflow limitation or COPD.

MEASUREMENTS AND MAIN RESULTS

The total sample size across all cohorts was 12,031, of whom 9,338 were from COPDGene. We identified five loci associated with emphysema-related phenotypes, one with airway-related phenotypes, and two with gas trapping. These loci included previously reported associations, including the HHIP, 15q25, and AGER loci, as well as novel associations near SERPINA10 and DLC1. All previously reported COPD and a significant number of spirometric GWAS loci were at least nominally (P < 0.05) associated with either emphysema or airway phenotypes.

CONCLUSIONS

Genome-wide analysis may identify novel risk factors for quantitative imaging characteristics in COPD and also identify imaging features associated with previously identified lung function loci.